滑移边界对含表面活性剂超薄液膜去湿特性的影响

Effect of slip boundary conditions on dewetting dynamics of ultrathin films covered by insoluble surfactants

针对预置在固体基底上含非溶性表面活性剂的超薄液膜去湿过程,基于滑移边界条件下的液膜厚度和表面活性剂浓度的非线性演化方程组,采用PDECOL程序对液膜去湿过程进行了数值模拟,分析了不同滑移尺度对含有内源和外源表面活性剂去湿特性的影响。研究表明,滑移边界对去湿过程的影响与表面活性剂初始分布密切相关,且不同平衡液膜厚度下滑移尺度的影响存在较大差异;总体上滑移边界促使超薄液膜趋于稳定,特别是当平衡液膜厚度较小时,滑移边界可有效控制去湿过程的发生;对于Spinodally稳定液膜,滑移边界对外源性情况的影响远大于内源性情况。

The dewetting of ultrathin liquid films in the presence of insoluble surfactant monolayer was studied.Under slip boundary conditions,coupled nonlinear evolution equations for film thickness and surfactant concentration based on lubrication theory were used.The dewetting evolution of films was simulated using PDECOL program,and the effects of slip length on dewetting dynamics,including endogenous and exogenous surfactant cases were investigated.Numerical results showed that the impact of slip boundary on dewetting process was closely related to initial surfactant distribution,and was obviously different under various equilibrium film thicknesses.Slip boundary generally played a role of improving the stability of ultrathin insoluble surfactant-covered films,and especially for small equilibrium film thickness,slip boundary could restrain the dewetting processes effectively.For spinodally stable films,the effect of slip boundary on exogenous surfactant dewetting was more noticeable than that on endogenous surfactant case.